1. Field of the Invention
This invention relates to administration of a medicinal fluid to a patient and, in particular, to low-cost, easy-to-use infusion systems for the intravenous dispensing of a fluid prescription.
2. Description Relative to the Prior Art
A wide variety of infusion systems are presently known in the medical art, particularly within the field of technology directed towards therapies requiring the use of intravenous medication. The administration of medication by intravenous delivery as prescribed by a medical doctor may be dispensed to the patient by an infusion system for certain therapies. The prescribed therapeutic liquid is referred to as the prescription or xe2x80x9cRxxe2x80x9d, and is usually supplied by a pharmacist in a container such as a disposable plastic bag for use with an infusion system. The plastic bags usually have attached to them various components or elements which are useful in the infusion process such as various tubes and elements to secure the bag in place, to transport liquids (e.g., prescriptions, water, nutritional supplements, analyze solutions, etc.) with respect to the patient, to support the elements of the container, etc. This composite arrangement is usually referred to in the medical art as a xe2x80x9csetxe2x80x9d. The set is then loaded into a fluid delivery device called the xe2x80x9cpumpxe2x80x9d either by a nurse or by the patient himself. Once the pump is connected to the patient, the device pumps the Rx through the conveying tubes of the set to infuse the patient.
The assembly of an infusion system, as presently known in the art, requires a certain degree of skill and manual dexterity. In some conventional infusion systems, the tubing of the set must be loaded into the pump, the set cleared, the set tubing meshed between rollers, and the roller gate closed. In a hospital setting, a nurse or medical technician is generally available to perform these dexterous steps and to instruct and/or supervise the patient in the loading and operation of the pump. It is also necessary for the physician, nurse or patient to program the rate of pump operation to control the fluid flow rate of the medication to the patient. Written records of the infusion system parameters must be generated and maintained for various medical reporting reasons. In the present day medical setting, many ill people are out-patients who must set up and operate their infusion system at home without the services of a knowledgeable practitioner to oversee proper assembly and performance of the system. Some patients may have debilitating illnesses or impacted conditions of memory dysfunction which leave them too weak or too forgetful to carry through complex assembly and programming procedures. With a rapidly growing aging population, many out-patient seniors may not have either the manual dexterity, physical strength, or mental acuity needed to cope with the demands of setting up and using current infusion systems. Additionally, with the downward economic pressures on all medical costs, and especially those of Medicare and Medicaid, a need exists for reducing the costs of these therapeutically essential infusion systems and minimizing the cost of technical assistance personnel.
U.S. Pat. No. 5,935,099 describes a menu driven reprogrammable drug pump is provided with a memory, such as flash memory, a display, a keyboard, and a communications port to allow a generic pump to be programmed with a desired pump application (therapy) program and patient specific settings. Programming and data transfer with another pump or a computer to and from the patient pump is by the communications port that allows local and/or remote communications with the pump. Flash memory stores the pump application program during use. Patient safety is provided by a cassette identification system, an occlusion detection system, and a latch/lock detection system. Automated testing of the pump is by a closed loop testing system. This system does not provide for unique pump identification, in combination with unique patient and therapy information. A limited range of pumping systems is also disclosed.
The present invention alleviates problems present in the prior art by providing a simplified, low-cost infusion system adapted for use both by in-patients in hospitals and by out-patients at home.
A therapy infusion apparatus for delivery of medicinal fluid to a patient may comprise:
a) a flexible therapy bag,
b) a movable surface which can apply force to an outside surface of the therapy bag to increase fluid pressure within said therapy bag,
c) an exit port in the therapy bag which will allow fluid to exit in a delivery direction from the flexible therapy bag under fluid pressure,
d) an adjustable, fluid control element located along the delivery direction, after the exit port.
The therapy infusion apparatus may be constructed with the therapy bag having at least one major face which comprises at least 25% of the total surface area of the therapy bag, and the movable surface can be moved into contact with the at least one major surface so that contact between the at least one major surface and the movable surface covers at least 50% of the surface area of the at least one major surface by the time that the movable surface is fully extended. The therapy bag may comprise at least two fluid flow ports within a fluid control element, one of the ports comprising the exit port, and adjacent to at least one of the ports is an element which has a storage area for a memory unit and access ports to the memory unit. The memory unit may comprise, for example, a chip (e.g., intelligence chip), and the access ports enable electronic connection from an outside memory reading or memory writing apparatus to the chip. The chip may be present within the storage area, and the chip preferably contains electronically readable information relating to at least two different topics selected from the group consisting of the prescription; the name of an active ingredient in the prescription; the chemical name of a prescription carrier; additives in the prescription; volume of the prescription; expiration date; name of a prescribing doctor; name of a private loader; name of a local supplier/manufacturer of ingredients of the prescription; source of at least some materials in the prescription; a name of a therapy bag manufacturer; a name of a pharmacist; a patient name; patient information relating to at least one of age, allergies, address, frequency of prescription refill, weight, chemical intolerances, instructions for a flow control module with respect to desired flow rates; intervals for delivery; rate and volume of delivery; and drip rate.
The therapy infusion apparatus preferably provides the movable surface as an extendable bladder which is expandable or inflatable by a fluid (e.g., liquid or gas) to move a surface of the bladder against a surface of the therapy bag.
A therapy bag for use in the infusion of liquids to a patient is described comprising a flexible bag having a storage area and a delivery end, the delivery end comprising at least two fluid ports, at least one port capable of allowing fluid from within said storage area when pressure is applied to liquid within the storage area, and the delivery end also having a storage area for storage of a memory element, the storage area having access ports for electronically accessing the memory element. The storage area preferably contains a memory storing element such as a chip and there are electronic access ports oriented in the storage area to allow external electronic access to the chip so that information on the chip may be accessed. The storage area may be asymmetrically located along the delivery end. At least two liquid flow ports may be located to one side of the asymmetrically located storage area. A battery may be located on the same side or the other side of the ports as the storage area for the memory unit. The battery may provide power to any electrical or electronic element on the pump or apparatus, such as at least one electrically powered element on the therapy bag selected from the group consisting of a display panel on the pump, a chip, a fluid rate control element, and an alarm (e.g., sound display, light display, vibration display, Radio Frequency signal, electronic signal with a connection to computer or communication system).
The infusion system of the invention is packaged in a structured support system, such metallic, polymeric, or other structural housing such as a light-weight nylon mesh container which houses basic components of the infusion device. The container, which is the system pump, may be provided with elements to secure the container to a patient. These patient attachment elements include belts, straps, harnesses, hooks, and associated apparel (e.g., a shirt, jacket, girdle, side-pack, back pack or the like having the container secured to a portion thereof or in a pocket). A preferred support element comprises a loosely overlying garment such as a harness, shoulder belt, waist belt, side-pack or backpack, such as one constructed of fabric, such as nylon straps, so the apparatus may be worn by an ambulatory patient. The container alternatively may be suspended from a fixed support for the patient immobilized in bed, in a chair or a vehicle.
A filled therapy bag containing the Rx to be infused into the patient is associated with the pump, causing a fluid connection element between the Rx and the pump as by insertion into the pump by the medical practitioner, such as by a physician, attendant, nurse or by the patient. With the therapy bag positioned in the pump, a movable (force-providing) surface (such as an inflatable bladder or moving wall element or moving plate located within the walls of the container, as for example with the therapy bag placed against an element) moves within the container walls to increase pressure to the Rx within the therapy bag. The pressure against the therapy bag may be provided by any element, especially any non-puncturing element adjacent to or comprising an interior wall of the pump which is in face-to-face (major surface or side-to-side) contact with the Rx filled plastic therapy bag. Force provided by against the inflated bladder provides the pressure within or on the prescription bag which enables the flow of the medication through the set.
An Electronic Control Unit (ECU), in the form of a semiconductor microcomputer, and its battery power supply are located within the structural housing, preferably within the pump""s assembly, as in a pocket, sleeve, housing, frame, pouch, lining or container of the pump. The ECU plugs into an element which connects memory or circuitry to the infusion system or within the set as with electrical wires, cables, plugs, connectors or printed circuit cable which electrically interconnects the various components of the system. The ECU has the potential to perform the functions of controlling the sequences of operation of the system and components, monitoring the performance of the system and individual components, and alerting the patient or a health supervisor of any noteworthy condition or malfunction of the infusion system or any part thereof. The ECU may include a ROM containing the microcomputer""s operating system, as well as operational programmed routines which include displaying data relating to the system status by means of visual display unit, such as an LED, LCD or other visual display which may be mounted on the pump, visible to the patient. The status data being stored in the ECU memory is also available for visual display on a monitor (CRT, LED, LCD, etc.) or later printout, even by means of a modem so that the information may be transmitted to a medical control station distant form the patient.
A fluid control module (FCM) may also be part of the set. The FCM comprises an inlet port, an outlet port and a frame. Its inlet port is to be connected to the therapy bag and its outlet port supplying medication to the patient is connected to intravenous tubing segment of the set by means of connectors such as male-female connectors, slidable inserts, clamped tubes, or hydraulic push-on connectors. Mounted in the FCM may be an electronically connectable source of information such as a chip, hardware, software source or semiconductor plug-in EPROM having encoded within it information such as information concerning the therapy medication, its dosage, rate of delivery, schedule of delivery, and other information which may relate to the patient and treatment. The software would be specifically designed for this operation, allowing ready access to insertion of therapy specific, patient specific, and pump specific information. Additional specific information may be accessed such as required storage conditions, actual storage conditions (e.g., a thermocouple could be read to show conditions during transit), and the like may also be addressed by the software. At the time of filling the prescription, the pharmacist enters the information into the source of information such as the EPROM chip by whatever information insertion means are available, such as by replacing a chip, loading a chip from or with his computer. The address bus of the ECU may be interconnected with an EPROM via an electrical printed circuit cable so that the ECU has access to the data and instructions stored in the EPROM relating to the specific bag therapy. A data storage element may be provided with a General Purpose Interface Buss (GPIB) for receiving and selection of appropriate data from the pharmacists required input. This information will be loaded onto the chip resident in the fluid control module. The information will usually be loaded at the tome that the therapy bag is being filled.
With the therapy bag and attached FCM loaded into the pump system, operation commences in one or two different manners. In one format, operation may start only after a security routine within the system (either hardware or software) checks to assure that a therapy code on the therapy bag and/or FCM matches a code in the pump. This assures that the therapy bag being loaded or inserted in or onto the pump is the proper therapy. After clearance by the security check, the operation may begin. An alarm or indicator may be provided to indicate an improper connection or record of misconduct in the use of the wrong therapy in the bag. These events may also be recorded in the pump buffer. Another format would begin operation when the xe2x80x9cstartxe2x80x9d button is depressed or a timed signal initiates the operation (e.g., from data in the EPROM). The coding in the EPROM is read by the ECU and a signal is sent to the FCM locking it up so that fluid cannot flow until such direction is given or allowed. Elements are provided to expand the bladder to a pressure level prescribed by pump logic so that contained liquid may be put under pressure. The pressing of the bladder may be by a plate or surface coming into contact with the exterior of the bladder, a collar moving along a surface of the bladder or any element which attempts to compact the space within the bladder. For example, a small air compressor under control of the ECU supplies air to the bladder whose pressure is monitored by a pressure transducer. The air compressor is cycled on and off by the microcomputer to maintain bladder pressure in accordance with the pressure value required by the Rx and encoded in the EPROM. A start-up program enables the user to bleed air out of the system when desired (even before fluid is actually pumped), and a message may be provided on the display of the ECU would then advise the user that the batteries are OK, and that the system may be connected to the patient""s body. With the intravenous connection made, the patient may then push the start button, and the programmed delivery is begun. Under control of the ECU, the FCM meters the flow of the medication by cyclically dispensing precise volumes of fluid through its outlet port. Each cycle of the FCM generates a signal pulse which is detected (e.g., simply by a counter, flow-meter, pulse meter, or other sensor meter) or by a detector such as a Hall-effect sensor, a photodiode or the like and the sequence of events or pulses is monitored by the ECU. Any failure in flow would cause an interruption of the stream of pulses from the Hall-effect sensor (or other sensor), and result in a shutdown of the system (the interruptions were designated as sufficiently extreme) and initiation of an alarm sequence by the ECU as will be explained below. Also, when a system shutdown occurs, a check valve in the set line to the patient""s body may actuate to preclude any back leakage from the patient""s circulatory system into the infusion system.
In the case of infusion of analgesics, a patient controlled analgesic (PCA) button on the ECU cooperates with the logic control loop to a) check with a buffer to see if patient controlled administration of the analgesic is permitted; b) if PCA is permitted, at what delivery rate or amount, the number of PCA""s, etc.; c) permit the patient to enhance or beef-up the paint control or the rate of administration in accordance with the steps outlined above, and provide a confirming signal (e.g., a sound signal); and d) in some cases, no Rx may be delivered, but the sound signal can be given as a placebo.
The elements of the infusion system may be assembled and programmed to operate either open loop or closed loop.